<nz-select nzMode="multiple" nzPlaceHolder="请选择角色" nzAllowClear nzShowSearch nzServerSearch
[(ngModel)]="selectedUser" (nzOnSearch)="onSearch($event)" class="select">
<ng-container *ngFor="let o of optionList">
  <nz-option *ngIf="!isLoading" [nzValue]="o" [nzLabel]="o.name"></nz-option>
</ng-container>
<nz-option *ngIf="isLoading" nzDisabled nzCustomContent>
  <i nz-icon nzType="loading" class="loading-icon"></i>
  Loading Data...
</nz-option>
</nz-select>